Ilmenichnus atherus Schlirf, 2011

Diagnosis: Ilmenichnus with upper surface covered by irregular pustules.

Description: More-or-less straight, dominantly horizontal, subordinately slightly oblique, unlined, uni-lobed U-shaped spreite burrows, with protrusive U-spreite lamina and a subordinate retrusive limb-spreite lamina with a ratio of open U-limb to spreite < 0.5. Surface with longitudinal and/or transverse, fine ridges and grooves. Upper surface with irregularly shaped pustules. Burrows generally filled with ovoid pellets. One specimen (SMNS L204 b) has a true side branch emerging from the limb, with enlargements at the point of branching (Fig. 8). Diameter of U-limb frequently enlarged towards distal burrow part.